Epidemiology of traumatic and ischemic brain injuries

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Epidemiology of traumatic and ischemic brain
injuries
G. Citerio Rianimazione H San Gerardo Monza
(Mi)
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Epidemiology

• Epidemiology is the study of the distribution
  and determinants of disease frequency
• Two elements
• Distribution (mortality, prevalence, trends)
• Determinants (predisposing conditions and risk
  factors)

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Incidence of traumatic brain injury (TBI).

• Using national data for 1995-1996, the CDC
  estimates that TBIs have this impact in the
  United States each year
• 1 million people are treated and released from
  hospital emergency departments
• 230,000 people are hospitalized and survive
• 50,000 people die

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TBI incidence rate

• Using preliminary hospitalization and mortality
  data collected from 12 states during 1995-1996,
  CDC finds
• The average TBI incidence rate (combined
  hospitalization and mortality rate) is 95 per
  100,000 population. Twenty-two percent of people
  who have a TBI die from their injuries.

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TBI risk factors, and causes

• The risk of having a TBI is especially high among
  adolescents, young adults, and people older than
  75 years of age.
• For persons of all ages, the risk of TBI among
  males is twice the risk among females.
• The leading causes of TBI are motor vehicle
  crashes, violence, and falls. Nearly two-thirds
  of firearm-related TBIs are classified as
  suicidal in intent.

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Age and sex
NL MI 97-98
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Age and outcome
p ? 0.0001
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Sex and outcome
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TBI risk factors, and causes

• The leading causes of TBI vary by age falls are
  the leading cause of TBI among persons aged 65
  years and older, whereas transportation leads
  among persons aged 5 to 64 years.
• The outcome of these injuries varies greatly
  depending on the cause 91 of firearm-related
  TBIs resulted in death, but only 11 of
  fall-related TBIs are fatal.

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Causes
Road traffic accident
Pedestrian
Fall/Precipitation
Domestic
Sport
Work
Assault
NL MI 97-98
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Outcomes divided by cause
Fall/Precipitation
Favourable
48
Work
Unfavourable
41
Domestic
72
Sport
88
Assault
80
Road traffic accident
39
Pedestrian
57
0
50
100
150
200
250
300
p ? 0.0001
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Chronic health evaluation
Knaus WA, Zimmerman JE, Wagner DP et al
Apache-acute physiology and chronic health
evaluation a physiologically based
classification system. Crit Care Med 1981
9591-597
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Chronic health evaluation
p ? 0.0001

• Prior good health B. Mild to moderate limitation
  of activity
• C. Serious but not incapacitating restriction of
  activity D. Restriction of activity

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• There was a 22 decline in the TBI-related death
  rate from 24.6/100,000 U.S. residents in 1979 to
  19.3/100,000 in 1992.
• Firearm-related rates increased 13 from 1984
  through 1992, undermining a 25 decline in motor
  vehicle-related rates for the same period.
• Firearms surpassed motor vehicles as the largest
  single cause of death associated with traumatic
  brain injury in the United States in 1990.

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Incidence and prevalence of TBI-related
disability.

• Based on national TBI incidence data and
  preliminary data from the Colorado TBI Registry
  that describe TBI-related disability in
  1996-1997, CDC estimates the following
• Each year more than 80,000 Americans survive a
  hospitalization for traumatic brain injury but
  are discharged with TBI-related disabilities.
• 5.3 million Americans are living today with a
  TBI-related disability.

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• There are many kinds of impairments that may
  occur as a result of TBI. These injuries may
  impair
• cognition -- concentration, memory, judgment, and
  mood
• movement abilities -- strength, coordination, and
  balance
• sensation -- tactile sensation and special senses
  such as vision
• TBI sometimes results in seizure disorders
  (epilepsy). About 1 percent of persons with
  severe TBI survive in a state of persisting
  unconsciousness.

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• There is no way to describe fully the human costs
  of traumatic brain injury the burdens borne by
  those who are injured and their families. 
• Only a few analyses of the monetary costs of
  these injuries are available, including the
  following estimate (lifetime cost of all brain
  injuries occurring in the United States in 1985)
• Direct annual expenditures      4.5 billion
• Indirect annual costs 33.3 billion
• Total costs 37.8 billion

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Disability in young people and adults one year
after head injury prospective cohort
studyS Thornhill, GM Teasdale, GD Murray, J
McEwen, CW Roy, KI Penny BMJ 20003201631-1635
( 17 June )
GOS Mild TBI () Moderate TBI () Severe TBI ()
Severe Disability 21 26 47
Moderate Disability 30 28 31
Good Recovery 49 37 22
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Disability in young people and adults one year
after head injury prospective cohort
studyS Thornhill, GM Teasdale, GD Murray, J
McEwen, CW Roy, KI Penny BMJ 20003201631-1635
( 17 June )
Specific problems Mild TBI () Moderate TBI () Severe TBI ()
Daily living at home 22 28 42
Daily living outside 34 38 67
Physical 58 66 82
Cognitive 43 49 76
Mood 47 48 76
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Primary prevention

• Primary prevention of TBI is an important goal of
  public health efforts. Accomplishing this goal
  requires attention to each of the major external
  causes of these injuries
• transportation,
• violence,
• and falls.

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1. Transportation

• Transportation crashes are the leading cause of
  TBI-associated death among women and persons
  under 15 years of age.
• Fortunately, the rate of TBI-associated death due
  to transportation crashes has decreased
  approximately 40 percent since 1980.

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1. Transportation

• This drop is likely because of a combination of
  factors
• - an increase in seat belt and child safety seat
  use,
• - an increase in the number of vehicles equipped
  with air bags,
• - and a decrease in the incidence of driving
  while intoxicated.
• These positive changes should receive continued
  support.

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Preventing traumatic brain injury an innovative
approach to outcomes

• 1-day educational injury prevention programme
  for young people with speeding offences
• Farmer J, et al Brain Injury 14109-15, 2000

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Rate of convictions after the target programme
date

• 92 programme participants and
• 87 non-treated individuals
• no significant between-group difference

Farmer J, et al Brain Injury 14109-15, 2000
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MOST program
Accident rate Injury rate Ticket rate
California
NY
McSwain N, et al J Trauma 30,101189-1199, 1990
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Epidemiology and prevention of traffic injuries
to urban children and adolescents.
Durkin MS, et al Pediatrics 103 66-74, 1999
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Costly achievements

• Education in a simulated traffic environment, and
  via theatrical performances
• Construction of new playgrounds to provide
  expanded off-street play areas for children
• Bicycle safety clinics and helmet distribution
• Supervised recreational and artistic activities

Durkin MS, et al Pediatrics 103 66-74, 1999
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Traffic related mortality and the reunification
of Germany
FK Winston, et al BMJ 318 1647-1650, 1999
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Renewed emphasis on law enforcement

• Seat belts
• Helmet
• Speed regulation
• Poison control

Passive protection works
Satcher D JAMA 284950, 2000
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Voluntary helmet use does not work
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Rate of seat belts use after law implementation
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Expected reduction of severe head injury
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2. Violence

• Violence is a leading cause of TBI--especially
  among males--and violence with firearms is the
  leading cause of TBI-associated death. Effective
  programs designed to decrease the occurrence of
  interpersonal and self-directed violence would
  help address this cause.

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3. Falls

• Falls are the third leading cause of
  TBI-associated death. Among women over 75 years
  of age and men over 85 years of age, falls are
  the leading cause of TBI-associated death. Falls
  are also a major cause of nonfatal TBI.
• Effective interventions may involve modifying the
  environment to reduce fall hazards and the
  impacts of falls and, where possible, reducing
  the use of medications with side effects that
  increase the risk of falling.

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Outcomes
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Outcome trendData from literature
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Unfavourable outcome
40
Favourable outcome
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Jennet
TCDB
Fearnside
EBIC
Maas AIR Neurosurgery 441286-1298 1999
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GOS 6 months
NL MI 9798
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GOS 6 months Pat. in coma
NL MI 9798
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GOS 6 months in coma, at least 1 reactive pupil
NL MI 9798
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STROKE
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• Stroke killed 158,448 people in 1998 and
  accounted for about 1 of every 14.8 deaths in the
  United States (is the most common
  life-threatening neurological disease).
• About 47 percent of these deaths occur out of
  hospital. Total mention mortality about 280,000.
• The morbidity of stroke, i.e., incidence and
  prevalence, is shared about equally between men
  and women. At all ages, more women than men die
  of stroke.

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Estimated prevalence of stroke by age and
sexUnited States 198894
population
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• When considered separately from other
  cardiovascular diseases, stroke ranks as the
  third leading cause of death, behind diseases of
  the heart and cancer. (CDC/NCHS)
• On average, someone in the United States suffers
  a stroke every 53 seconds every 3.3 minutes
  someone dies of one.
• Each year, about 600,000 people suffer a new or
  recurrent stroke. About 500,000 of these are
  first attacks, and 100,000 are recurrent attacks.
  (Framingham Heart Study, NHLBI)

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• The most common variety of complete strokes is
  atherothrombotic brain infarction, which accounts
  for 61 percent of all strokes (excluding TIAs).
• The next most common is cerebral embolus (24
  percent). (44-year follow-up of participants and
  20-year follow-up of their offspring, Framingham
  Heart Study, NHLBI)

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• Of incident definite or probable strokes reported
  in the the NHLBIs ARIC study, 83 percent were
  ischemic, 10 per-cent were intracerebral
  hemorrhage, and 7 percent were subarachnoid
  hemorrhage. Among the 178 definite thrombotic
  brain infarctions, 38 percent were classified as
  lacunar strokes (in small blood vessels) and
  twice as many were in blacks as in whites.
  (Stroke, 199930736743)

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• 7.6 percent of ischemic strokes and 37.5 percent
  of hemorrhagic strokes result in death within 30
  days. (Stroke, 199930736743)
• About 4,500,000 stroke survivors (2,200,000 males
  and 2,300,000 females) are alive today.
• From 1988 to 1998, the stroke death rate fell
  15.1 (15.5) percent, but the actual number of
  stroke deaths rose 5.3 percent.

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Risk factors/1

• ATHEROGENIC HOST FACTORS
• Hypertension (?160/95 mmHg, RR 3.1 male, 2.9
  female)
• Blood lipids (elevated total/HDL colesterol
  ratio, RR 1.6 male, 1.8 female)
• Diabetes (RR 1.8 male, 2.2 female)
• Obesity
• Heart disease
• Race

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Risk factors/2

• ENVIRONMENTAL FACTORS
• Cigarette smoking (increased risk of SAH, RR 4-9,
  and stroke)
• Oral contraceptives (RR 5)
• Heavy alcohol consumption (U shape relationship)
• Physical activity

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Estimated 10-Year Stroke Risk in 55-Year-Old
adults according to Various Risk Factors
Framingham Heart Study
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Stroke prevention

• Reducing elevated blood pressure
• Cessation of smoking
• Warfarin anticoagulation in AF
• Increasing physical activity, weight reduction
• Reducing elevated blood lipids

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